The purpose of this project will be to model NF1 syndrome associated glial malignancies using a novel system for random, transposon-based, somatic insertional mutagenesis developed in the Largaespada laboratory. The development of malignancy is a serious and feared aspect of NF1 syndrome. Little is known about germline alterations that could predispose some NF1 patients to these malignancies. While some insight has been gained in the somatic changes that can occur in NF1 syndrome-associated malignant tumors, it is likely that much remains to be learned. An unbiased screen for somatic mutations that could accelerate malignancy after NF1 gene loss in a model could provide a list of candidate genes to examine for alterations in human NF1-associated malignancies and genes that could influence germline susceptibility. The Largaespada lab has developed a system for random, transposon-based somatic mutagenesis that can be used in forward genetic screens for cancer genes in mice. The system uses the Sleeping Beauty (SB) transposon, which is a synthetic, Tc1/mariner family transposon derived from Salmonid fish. This system was used to accelerate sarcoma development in p19Arf-/- mice and, after some modification, to induce lymphoma, medulloblastoma, and astrocytoma in wild-type mice. In this proposal SB-based somatic mutagenesis will be applied to Schwann cells in the context of a wild type background, loss of the Nf1 gene or EGFR overexpression in mouse models.